No Operator Error - Helpful Tips for Mechanical Rigging

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There may come a time in a rigger’s life when he or she will need to create a mechanical rig. While it may seem simple compared to a character rig, there are some very important things to consider when tackling this type of project. Let's go over some tips that will get you creating great mechanical rigs that every animator will enjoy.
Know How the Rig Needs to Move
In order to create a proper rig for a mechanical object, whether it's a crane, helicopter or some type of vehicle, you need to have an understanding of how it should move. For example, if you're rigging a crane to be animated, how does that particular crane move? Where are the moving parts? Mechanical rigging can be quite a bit different than character rigging because everybody has a general understanding of how the human body moves, which means you know how your character rig should move to be realistic and where the joints need to go. Getting the proper movement for your object may mean doing a bit of extra research on the particular mechanical element you are going to be rigging.
It's also important that you know how the rig needs to move for the particular shot. Are there any limitations given to it? And what type of animation will be needed for it? Is there movement that can be automated? These are all questions that, when answered, can help determine what your rig needs. For example, if this is some type of vehicle that needs to drive forward you don't need to have the animator manually animate the wheels rotating for each frame when it could be automated through an expression, which can save a tremendous amount of time for the animator.
Keep the Rig Simple
When creating a mechanical rig whether it's for your own personal project or a project within the pipeline you need to make sure that the rig you create is simple enough so that it's not confusing to whoever is going to animate it. It's no surprise that a typical character rig can get up to the hundreds if not thousands of controls to give the animator as much flexibility as possible. This however is usually not true when it comes to creating a mechanical rig. Most often you will not need a complex rig setup to achieve a believable mechanical animation, and you definitely will not need to spend the time to add in any secondary controls like squash and stretch that you would typically find in a character rig.
This is really where the first tip can become very beneficial to you. If you know what the object is going to be used for, you can build the rig around that. For instance, maybe it's a crane, and the only animation that needs to be done is to have the crane pick up and move a large steel beam. That's a simple enough animation to where the rig setup can be just as simple. There is no need to spend extra time creating complex controls that will never be touched by the animator.
Incorporate Set Driven Keys & Expressions
Set driven keys and expressions are two vital tools at a rigger’s disposal that can help create a great mechanical rig in a short amount of time that also speed up the animation process tremendously. If you are unfamiliar with set driven keys and expressions, they are used to automate simple tasks that would otherwise take a long time to hand keyframe.
There are many places where this could be utilized in a mechanical rig, such as creating a set driven key that automates the raising and lowering of a cranes pulley by simply adjusting the attribute for the driven key. You could then use an expression that automates the rotation of the gears based on the movement of the cranes cables. Now you have a whole complex animation happening from only one single set driven key attribute for the cranes pulley. Everything else gets automated accurately, saving a large amount of time during the animation phase. While these types of things may not be as valuable for a character rig where an animator would not want movement automated for them, it is however extremely helpful for mechanical animations where things are less reliant on the 12 principles of Animation.
Make the Rig Animator Friendly
In order for a rig to be complete you must create control curves for the animator to use. These curves should not only be easily visible, but they should also be named properly to what they affect on the object. A good naming convention is extremely important for having an animator-friendly rig anyone can understand. You should also be clearing out the attributes for each control that won't ever need to be animated. For example, locking and hiding scale attributes will simplify the attributes, and will only show the animators what needs to be animated so they don't have to worry about the other attributes that won't have any effect on their animation.
Now that you are familiar with these tips try incorporating them into your next project! If you want to learn more check out this Modeling & Rigging a Hydraulic Crane in 3ds Max tutorial and other rigging tutorials listed below, and don't forget to come back to the blog for more helpful articles!